Effects of Pilot Injection Timing and EGR on a Modern V6 Common Rail Direct Injection Diesel Engine

Nitric oxide and smoke emissions in diesel engine can be controlled by optimising the air/fuel mixture and combustion temperature. Early in-cylinder diesel injection that produces premixed charge can simultaneously reduce NOx and smoke emissions. However, there could be an increase in hydrocarbons and CO emissions due to fuel impinged to the cylinder wall. The focus of the present work is on the effects of a variation of pilot injection timing with EGR to NOx and smoke level of a modern V6 common rail direct injection. This study is carried out at two different engine load conditions of 30 Nm and 55 Nm, at constant engine speed of 2000 rpm. Emissions of NOx are measured from the exhaust sample line by an exhaust gas analyzer (Horiba MEXA-7100EGR). Smoke level is measured by using an AVL 415S smoke meter which provides results directly as a Filter Smoke Number (FSN) unit. The results show that the early pilot injection timing contributed to the lower smoke level and higher NOx emissions. The higher level of NOx is due to higher combustion temperatures resulting from the complete combustion. Meanwhile, the lower smoke level is due to complete fuel combustion and soot oxidation. The early pilot injection timing produces an intermediate main ignition delay which also contributed to complete combustion. The formation of smoke is higher at a high engine load compared with low engine load is due to the higher amount of fuel being injected, resulting in higher smoke formatio

Mathematical modeling and performance study of Fischer-Tropsch synthesis of liquid fuel over cobalt-silica

AbstractA numerical one-dimensional pseudo-homogeneous mathematical model of a fixed bed reactor for Fischer-Tropsch (FT) synthesis was developed over a simulated nitrogen-rich syngas (33% hydrogen, 17% carbon monoxide and 50% nitrogen (volume basis)), on a cobalt-silica catalyst. An algorithm was developed and the MATLAB codes were written in order to predict the product selectivity (H2O, CO2 and hydrocarbons i.e. CH4, C2, C3, C4 and C5+) and syngas conversion (CO and H2). In order to predict the kinetic parameters, the global search optimization subroutine (from MATLAB Global Optimization) was used. The model was fitted with experimental data at five different operating conditions with respect to conversion and selectivity. Discrimination between the model and the experiments was determined by the mean absolute relative residuals percentage (MARR %) and the value was 13.29%. The Effects of operating conditions such as reaction temperature, total pressure, flow rate and H2/CO molar ratio were investigated on the catalytic performance of the cobalt-silica for synthesis of liquid fuel. The model was studied in the range of 200-260°C, 1-25bar, reduced gas flow rate (per unit mass of catalyst) of 2.4-3.6 NL gcat-1 h-1 and H2/CO = 1.75-2.75 (mole basis)

Tribological Performance of Biomass-Derived Bio-Alcohol and Bio-Ketone Fuels

This study relates to developing future alternative fuels and focuses on the effects of a fuel’s molecular structure on its properties and performance in advanced propulsion systems. The tribological performance of various biomass-derived oxygenated alternative fuels, including butanol, pentanol, cyclopentanol, cyclopentanone, and gasoline and their blends with diesel, was investigated. Lubricity tests were conducted using a high-frequency reciprocating rig (HFRR). Cyclopentanone-diesel and cyclopentanol-diesel blends result in smaller wear scar sizes compared to using their neat forms. A lower steel disc contaminated with the alternative fuels during the HFRR tests resulted in worn surface roughness values lower than those of the neat diesel by up to 20%. It is believed that these reductions are mainly due to the presence of the hydroxyl group and the carbonyl group in alcohols and ketones, respectively, which make them more polar and consequently helps the formation of the protective lubrication film on the worn moving surfaces during the sliding process. Overall, the results from this study indicate that environmentally friendly cyclopentanol and cyclopentanone are practical and efficient fuel candidates for future advanced propulsion systems

The significance of low carbon bio-alcohols and bio-ketones fuels for clean propulsion systems

This experimental work investigates oxygenated bio-fuel component blends of butanol, pentanol and cyclopentanone with diesel on the combustion characteristics, gaseous emissions and particulate matter (PM). Furthermore, PM characteristics, including size distributions, morphology and nanostructure are investigated.The oxygen content on the sustainable fuel blend components (bio-alcohols and bio-ketone) and the lower cetane number leading to a longer ignition delay, larger premixed combustion phase and high mean peak combustion temperature reduced the total number of particle concentration by up to 91%. Characterisation of particles demonstrated morphological and nanostructural alterations, such as the reduction in primary particle size that would lead to greater particle oxidation reactivity. Furthermore, the combustion of oxygenated blends showed a reduction in the total hydrocarbon emissions and an increase in NO2 concentration. This research provides new knowledge to understand the effects of fuel properties on gaseous and particle emissions formation and characteristics. Overall this work demonstrates bio-alcohols and bio-ketones as low carbon fuels in unveiling strategies for vehicular emissions abatement

Influence of the addition of LPG-reformate and H2 on an engine dually fuelled with LPG–diesel, –RME and –GTL Fuels

AbstractDual fuel compression ignition engine has been proposed as one approach to reduce diesel engine regulated emissions (NOX and Soot) and to also allow the utilisation of other non-traditional fuels in transportation, in order to improve fuel security and CO2 emissions. In an attempt to improve the combustion characteristics of the LPG–diesel dual fuelled engine the influence of the (a) hydrogen and reformate (H2 and CO) additions and (b) properties of the in-cylinder injected diesel fuel, in this case diesel, biodiesel and synthetic diesel fuel were investigated.Improvements on engine thermal efficiency and HC (including particular HC species) emissions with the reformate and further improvements on CO, soot and particulate matter with hydrogen with respect to LPG–diesel dual fuel combustion were obtained. However, an increase in NOX was obtained due to the high in-cylinder temperature as a result of the shorter advanced premixed combustion. Moreover, the RME’s oxygen content, different injection (i.e. different high bulk modulus) and combustion characteristics as a result of its properties modified the combustion process and hence produced even lower HC, CO, soot and PM emissions. On the other hand, the lower density of GTL has changed the diesel fuel injection and combustion characteristics in dual fuelling mode which resulted in the increased regulated (HC and CO) and unregulated emissions. However, LPG–GTL dual fuelling with reformate and H2 addition showed better smoke-NOX trade-off compared to that of ULSD and RME